Conventionally, a gas meter for measuring gas usage flow rate, equipped with security functions, for example, for shutting off a gas supply path when a problem has occurred during the use of gas, is available. As security functions, for example, a function for shutting off a gas supply path using a shutoff valve when a tremor not less than a predetermined seismic intensity has been detected by a seismoscope and a function for shutting off a gas supply path when the flow rate of gas has exceeded a predetermined value or when the usage time has exceeded a predetermined time are provided.
In addition, Patent document 1 discloses a gas meter control system that stops gas supply using a communication line for automatic meter reading or a prepaid card system when a usable amount of gas has been reached in order to supply an amount of gas corresponding to the payment of bill. Furthermore, Patent document 2 discloses a network system that automatically measures the usage amount of water, electricity, gas, etc. so as to be able to perform bill calculation, bill charging, water leakage check, transfer of electric leakage and gas leakage detection information, etc. Still further, Patent document 3 discloses a gas management system that shuts off the supply of gas using a prepaid card when the balance information of a gas bill has reached zero, thereby eliminating the need for meter reading and bill collection.    Patent document 1: Japanese Patent Application Laid-open Publication No. Hei 8-5398    Patent document 2: Japanese Patent Application Laid-open Publication No. 2005-18720    Patent document 3: Japanese Patent Application Laid-open Publication No. 2002-74497